The present invention concerns a machine for creasing and slitting of a travelling web, such a machine having means designed for setting the operating position of the tools perpendicular to the travelling direction of the web, at least one storage device with at least one spare tool, means for transferring a tool from an operating to a spare position and back and means for rotatably driving the tool while in the operating position.
It is an established fact that such a machine can, for instance, be situated after a corrugator and is part of a continuous line of machines which will transform a web of a paper wound up in reels into a continuous web of corrugated board. At the outlet of the corrugator, the web thus produced is slit, for instance, into two webs, whereupon each web is cut crosswise into sheets. The sheets are then taken one-by-one to a cutting machine which is designed for shaping box blanks, cases or other forms of packages therefrom.
In a machine for slitting and creasing, every changeover to a new run of sheets to be produced requires a replacement of certain slitting and creasing tools with other tools and repositioning of every tool in the crosswise direction, that is to say perpendicular to the travelling direction for the web to be processed.
In order to adapt the machine to the size of the new run of sheets and for reasons of production which, in the present case, essentially refer to the corrugator, serious consideration must be given to the possibility of very quick replacement and repositioning of the tools, for example changeover of the processing size and a degree of dispensing from varying the speed of the corrugator.
Numerous solutions have already been put forth with a view to reduce the time required for changing operation sizes. As both the slitting and the creasing operations are achieved ordinarily by means of a tool and an appropriate counterpart, such tools have, up to now, generally been fitted on a first rotary shaft and the counterpart on a second rotary shaft that extends parallel to the first shaft with adjustable distance between the axes of the two shafts. The tools and their counterparts which are simply referred to as "tools" hereinafter, are fitted so as to be shifted and set in a fixed position on the respective shafts, as required by the size of the blanks or the width of the web to be produced. Moreover, a similar processing station can be made up, either with a single pair of shafts on which the tools and counterparts are fitted for slitting and creasing purposes or else with two pairs of shafts, one of which carries the tools and the slitting counterparts and the other pair which has the creasing tools.
Hereinafter, it will be admitted that a slitting and creasing station includes at least a rotary tool and a rotary counterpart between which the web will travel as it is processed. Consequently, it can be noticed that among the solutions put forth up to now with a view for accelerating the step of changeover of the operation sizes, almost all consist in fitting at least one more pair of shafts as spare shafts and also equipped with tools and counterparts in the vicinity of the pairs of shafts in the operating position, for example so that the web will pass through the operating pair of shafts as well as the pair of shafts that are for the spare tools. So, with the changeover of the operating size, the pair of shafts in the operating position will be shifted into another "spare" or retracted" position whereas the spare shaft pair is shifted into an operating position. These shafts can be shifted into and out of the operating position with a crosswise motion, as described, for example, in German Patent Document 23 06 296, or with a circular motion, as disclosed in U.S. Pat. No. 3,489,043.
Further propositions envisaged two operating stations arranged in the web travelling direction with the rollers of the station being necessarily in the operating position, whereas the other rollers of the second station are kept in the spare position and vice-versa. This arrangement is disclosed, for example, in U.S. Pat. No. 3,408,886 and French Patent Document 2 244 620.
All of these solutions have, however, the following drawbacks:
There is no possibility to adjust the operating pressure between the tool and its counterpart fitted on a pair of shafts independently from one of the other pairs of tools fitted on the same shaft. In fact, this pressure cannot be the same for all tools, since it originates actually from the strength with which the two shafts are pressed against one another.
A second disadvantage is that with a pair of shafts in the operating position, there is no possibility to vary the crosswise portion of a tool counterpart with regard to its tool.
A third disadvantage is that, since all of the tools of one and the same shaft pair are compulsorily to move simultaneously from an operating to a spare or retracted position and back, the number of possible combinations of the tools usable within a machine is relatively small.